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Date: Thu, 16 May 2024 10:26:51 +0200
From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>, akpm@linux-foundation.org,
	shy828301@gmail.com, nao.horiguchi@gmail.com,
	xuyu@linux.alibaba.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm/huge_memory: don't unpoison huge_zero_folio
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References: <20240515023607.870022-1-linmiaohe@huawei.com>
 <e1c93779-8cde-4986-85d3-2134fb8970b3@redhat.com>
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On Wed, May 15, 2024 at 05:55:39PM +0200, David Hildenbrand wrote:
> > +	if (is_huge_zero_folio(folio)) {
> > +		unpoison_pr_info("Unpoison: huge zero page is not supported %#lx\n",
> > +				 pfn, &unpoison_rs);
> > +		goto unlock_mutex;
> > +	}
> > +

Sorry for spamming your reply David, but for some unknown reason I am not able
to find the original patch in my mailbox, in none of the two accountes I am
subscribed, so I guess I will have to reply here.

Just two things

1) We do not care if someone grabs a refcount for huge_zero_folio,
   because since it is not supported anyway the outcome will not change.
   Also, AFAIK, there is no chance we can unpoison that folio.
   Therefore, I would just lift the check two blocks and place it right after
   the hw_memory_failure check.

2) The whole thing is unsupported, but you will return -EBUSY while you
   should be returning -EOPNOTSUPP AFAICS.

with that you can add:

Reviewed-by: Oscar Salvador <osalvador@suse.de>

 

-- 
Oscar Salvador
SUSE Labs